“It’s hard to say this is a bad bill,” Tester told the Center for Public Integrity in an interview. “It saves money and adds disclosure, so what could be bad about that?”

The Congressional Budget Office has estimated that taxpayers would save about $500,000 a year if senators electronically filed these reports.

Nearly all federal candidates and committees began electronically filing their campaign finance reports with the Federal Election Commission in 2001. But the Senate was exempted from the e-filing requirement.

Yet the bill’s fate is likely controlled by just one man: Senate Majority Leader Mitch McConnell, who campaign disclosure advocates accuse of blocking similar legislation in years past.

McConnell’s plans this year for the Senate Campaign Disclosure Parity Act are unknown. Representatives of the Kentucky Republican did not respond to a request for comment for this story, nor did spokespeople for President Donald Trump.

Tester said his goal now is to get a “good bipartisan push” for the bill so that McConnell “won’t be able to say no.”

That includes conservative Republicans — such as Sens. Joni Ernst and Chuck Grassley of Iowa — as well as liberal darlings like Sen. Elizabeth Warren, D-Mass., and Sen. Bernie Sanders, I-Vt.

Then add at least three of the five newly minted Senate Democrats — Tammy Duckworth of Illinois, Maggie Hassan of New Hampshire and Chris Van Hollen of Maryland. All are expected to co-sponsor Tester’s bill.

Meira Bernstein, Hassan’s press secretary, told the Center for Public Integrity that “increased transparency in campaign spending is critical to our democracy.”

Added Van Hollen: “I strongly support the effort to make the electronic filing of campaign finance reports mandatory so that everyone can easily find out who is contributing to candidates for U.S. Senate.”

Meanwhile, four other sitting Democratic senators, each of whom did not sponsor the bill in the last Congress — Sens. Tammy Baldwin of Wisconsin, Michael Bennet of Colorado, Bob Casey of Pennsylvania and Patty Murray of Washington — expressed support for Senate campaign finance e-filing.

“Sen. Murray plans to co-sponsor this bill when it is reintroduced,” said Eli Zupnick, a spokesman for the assistant Democratic leader.

“We plan to co-sponsor,” said Bennet spokeswoman Laurie Cipriano.

“We support the policy and have no other comment at this time,” said Casey spokeswoman Jacklin Rhoads.

Furthermore, seven other sitting Republican senators and two other sitting Democrats have previously co-sponsored the e-filing bill, some as recently as 2014.

Those lawmakers are Sens. Lamar Alexander of Tennessee, John Cornyn of Texas, Mike Enzi of Wyoming, Lindsey Graham of South Carolina, Orrin Hatch of Utah, Johnny Isakson of Georgia, John McCain of Arizona, Brian Schatz of Hawaii and Jeanne Shaheen of New Hampshire.

It’s unclear whether any of these senators plan on co-sponsoring the Senate Campaign Disclosure Parity Act this year. Spokespeople for these lawmakers either did not respond to requests for comment or said the senators were still in the process of reviewing the legislation.

Officials for the Senate’s two newest Republican members — John Kennedy of Louisiana and Todd Young of Indiana — declined to comment for this story, as did a spokesman for first-term Democratic Sen. Catherine Cortez Masto of Nevada.

The Senate’s two other Democrats — Bill Nelson of Florida and Debbie Stabenow of Michigan — have never previously co-sponsored earlier versions the Senate Campaign Disclosure Parity Act.

Nor have the 31 other Senate Republicans, even though 12 of them had prior experience e-filing campaign finance reports as members of the U.S. House of Representatives.